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  1. #556
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    On the topic of port contours and flares unfortunately this does not solve the issue of port pipe organ resonances.

    On the AVS forums Erin has used Klippel to test and measure pipe organ resonance in number of JBL systems. From my observation the smaller LSR monitors suffer these problems. Yes it is audible according to Erin. This type resonance is a function of the enclosure air volume relative to the port air volume. A long port tube is required in a small enclosure volume compared to a shorter port in a larger enclosure of identical port tuning frequency.

    The only definite solution is to use a passive radiator. Focal and several other near field monitor manufacturers have used passive radiators successfully.

    In terms of overall listening satisfaction consider the following trade off:

    Is an over damped bass reflex design using a low port tuning frequency with a long port more important than risking audible pipe resonances in the midrange?

    In a small two way system probably not.

    Looking at the alternatives with a 3 way system you can limit the bandwidth of the woofer to avoid pipe organ resonances. But this adds cost and complexity to a commercial product.

    Adam and Focal both have premium 3 way near field monitors but they are beyond the budget of most home studio set ups.

    The passive radiator suddenly becomes an appealing option. But suitable panel real estate is required. For this reason passive radiators are now available in rounded rectangular shapes.

    An external powered sub woofer is another alternative. The main loudspeaker can use set up as a sealed enclosure while a seperate dedicated subwoofer uses an optimised bass reflex tuning. The advantages are powerful extended low bass. Tight upper bass and low colouration mid range.

  2. #557
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    HIGH-FREQUENCY HORNS, REALLY??

    The revenge of the mid/high dome...

    A number of my colleagues here only have an ear for the horn, discarding the dome idea with no hesitation. Well, if they really knew they'd possibly keep the other ear open for... the dome! This is part of an interesting discussion from Eargle's Loudspeaker Handbook, comparing dome vs horn distortion. Guess who wins, no not that one, out of your comfort zone i assume.

    I know this is not what you'd like to hear, it couldn't be, absolutely impossible, will never happen, etc. Nevertheless its true the dome has in fact less distortion than the horn, level for level. Ouch, you may be hurting now, with all this horn hardware. However, it is what it is, sorry.

    And while they cope with horn distortion in the 5% range i enjoy music with only 1-2% distortion from my domes, sounds fair to me! Horns are largely an output (SPL, impact) game, with pattern control (dispersion) being another important aspect of these.

    Who really needs 125-130 db capability in a home environment, where most of the listening takes place. I sure don't. Maybe the odd guy does. Some of the best (faithfull) monitors made, e.g. B & W 801, ATC SCM 300, some Genelec, etc. don't even use horns, instead have cones and domes.

    This is not intended to shame anyone here, nor their system, i simply find the situation rather fun when the small dome speaker (mid and/or high) presents less distortion than the larger horn hardware...

    I need to shoot a few pics to post here, as they explain the matter. Should come soon.

    Richard
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  3. #558
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    Hi Richard,

    I am not convinced that domes have lower distortion across the board. A lot has happened in both dome driver and horn driver manufacturing in recent times. If you subscribe to Voice Coil they regularly test both dome and compression drivers.

    JBL seems to have mastered the art of wave guides using soft domes in their LRS 3 series.

    It really depends on the application? The bandwidth of the transducers, actual SPL test levels and the type of test. sine wave or FFT.

    Below is a test by a reputable horn supplier to the diy market in Canada. See the distortion levels.

    https://josephcrowe.com/blogs/news/r...-1200-biradial

    Then there is the sound. Both domes and horns have a following.

  4. #559
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    First group of 3 pics regarding horn vs dome distortion. All pics are text from JBL's Engineer John Eargle,

    Loudspeaker Handbook, 2nd ed., Pages 200, 201, 249, 253, 256 and 258.

    Richard
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  5. #560
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    Example of a more rapid flare horn (and higher cutoff frequency) with a positive impact on distortion.

    Richard

    P.S. Another group of 3 pics to come, there's a presentation order/logic so that less familiar members can follow too. These might be the juiciest ones.
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  6. #561
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    The last 3 pics of the dome vs horn distortion issue.

    My comments on this will follow in the near future. The very last pic re ATC will be explained at that time (not about dome vs horn distortion per se).

    Please don't repost the pics elsewhere.

    Richard
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  7. #562
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  8. #563
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    This link illustrates the relationship of distortion in typical compression drivers

    http://www.cieri.net/Documenti/JBL/T....1,%20No.8.pdf

  9. #564
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    This link illustrates thd in the LSR 6300 monitors

    http://www.cieri.net/Documenti/JBL/T...3,%20No.2A.pdf

  10. #565
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    Trends in monitor design

    Near field monitors now dominate studio monitor sales.
    Nearly all near field monitors are active self powered designs.
    The reference level for near field monitors using a DAW console is 82 db with headroom of +20 db (102db).
    Numerous two way near field monitors employ a HF wave guide to control directivity and reduce THD of the HF driver in the crossover region.
    Premium near field monitors are three way designs with built in active amplification.

    The above trends point to lower monitoring levels and compact formats where direct radiators have an advantage.

    Larger control rooms used by major record labels still use large legacy monitoring systems. But the trend is moving towards multi monitor 7.2.4 mid field systems for recording Atmos sound tracks and Atmos music recordings. Large monitors are simply not practical for multi channel bed layer 7.1 formats.

  11. #566
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    COMMENTS ON THE SIX PICTURES REGARDING HORN VS DOME DISTORTION

    Following my last post i sense that horn fan hearts might bleed, or maybe in denial mode from the distortion news. Although Eargle isn't the only one having such info. Each user group benefits of something: with horns its mainly SPL and pattern control, whereas with domes its lower distortion sound. You can't win them all. And don't worry we'll still like the horn guys here even though they project too much distortion, lol

    1rst pic

    The normal operating levels mentioned, 95-110 db, is higher than one might have anticipated, pretty high. That wasn't expectted i guess. But i'll take the good news, its free and i'm a dome man. On the other hand this db range is consistent with Eargle's example where he's using a 107 db level for dome distortion assessment.

    2nd pic

    At least we know where the horn's distortion comes from, thermodynamic high pressures, and the remedy of increasing the horn's flare rate.

    3rd pic

    Distortion in a horn can be measured, as well as calculated (there's a math formula for this). It involves, among other things, the intensity at the throat. There's also a graph helping to solve the equation, which i haven't posted and hesitate to do so, since it might be proprietary info? (its absent from Tech Note V 1, No 8 about horns).

    Quickly, for this exercise Eargle tested two horns, 2352 and 2360, using the same 2446 driver, both at 107 db. The choice of a 107 db level (6 db lower than CD/horn 113 db sensitivity) doesn't appear to be an accident. Looks like a deliberate decision in order to match with the assessed dome's 107db capability, the level for level mentioned.

    Distortion was measured and also calculated with the formula/graph. At the top of this pic it says "a difference of about 1.3 db". That's the difference between the calculated vs the measured distortion for the horn. A 1.3 db distortion discrepancy between the two methods isn't large enough to call your mom and share drama...

    4th pic

    The dome example Eargle used is a fairly low power unit at 25W (again probably to match the 107 db level of his horn comparision). The raw domes i have cover the 30-100W range. A number of dome tweeters do take 100W and can do 115 db when their sensitivity is 95 db (i have pairs).

    The lowest program material capacity domes i have, the 30W Hi Vi Research, was purchased mostly for their response. They have a pretty flat frequency response from 2 khz out to 25 khz!, except for a small bump at 10 khz, while my EQs have a slider at 10 khz so its an easy correction, say -2db and you're done. In addition it was a great bargain for a pair of small 2-way satellite speakers that i can biamp with the bass cabs when i want.

    5th pic

    Eargle refers to a comparison and data review in Fig. 7-22C, this is actually where he compared the two horns distortion, 2352 and 2360 (3rd pic). Here using the same 107 db level to assess distortion in the 25W dome tweeter described. Needless to say the horn is about at "idle" with such level, whereas that dome is at the end of its rope, but nevertheless has lower distortion.

    His mention of the dome producing somewhat less HF distortion appears to be trying to avoid offending the horn crowd. Because when doing some simple calculations the numbers speak for themselves. Taking the middle of the 1-2% range for the dome is 1.5% a reasonable assumption, and the horn's 5% mentioned. Well, this would mean the horn has 3 times more distortion than the dome! Now with the same dome assumption, but this time assuming an even better horn with about 3% distortion, the dome would still have half of the horn's distortion.

    6th pic

    The ATC mid info given was not intended to be part of some monitor trend. It was shown as an example of more powerful dome mids available, than what Eargle used. His example of ATC 150W 115 db dome mid and my own 100W 115 db dome tweeters meet most level requirements. The lingering question of dome output capability to reach a certain level isn't really one, except for the extreme level monitoring.

    Sadly there isn't as many dome mids left on the market, with good performance and reasonable cost, compared to prior times when, for example, the initial Peerless and Vifa in Denmark had some decent models that didn't break the bank. The ATC type domes go for a fair amount of money. I've looked at a number of others, many are poor quality or performance (e.g. frequency response deviations, quite low sensitivity), while good ones seem to have inflation built-in.

    When i get time I'll post an example of a former good mid dome value (price/performance) that later went down the drain when it was reissued by other well-known manufacturers. Supposedly the replacement copy of it, well its outrageous...

    Richard
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  12. #567
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    The post about Crowe (# 558 here) doesn't help the poster, nor does the Tech Note V 1, No 8 about horns, in view of the horn distortion percentages reported below.

    First, things seem to be mixed up on Crowe's side regarding the actual horn used. Crowe says the RCF CD is on his ES 800 Biradial horn but his graphs show its on the ES 1200 Biradial.

    As for the distortion levels i was referred to there's a little catch there. Recall that Eargle used a 107 db level in order to compare two horn's distortion, as well to compare dome vs horn distortion.

    However, Crowe uses 85 db and 95 db SPL to assess horn distortion. This is pretty low levels for a compression driver/horn combo. Driving such at 85 db (or 95 db) seems like the waste of a driver/horn. A dome driver could easily do these levels for a lot less money, less distortion and probably flatter response.

    Moreover, there's at least a 12 db level difference between Crowe vs Eargle tests, not a trivial amount. No wonder Crowe's horn distortion numbers may look attractive, its a less demanding testing situation. 12 db or more output would impact negatively Crowe's distortion numbers for sure. Maybe why he chose lower horn levels than others?

    As for the Tech note it indicates that horn distortion has little to do with voltage drive but instead more an acoustical output matter. JBL's own distortion numbers in that note: 2445/2360 at 25% dist. measured (26% calculated), and 2425/2327/2360 at 40% dist. measured (48% calculated). These numbers are at 10 khz. Looking at a Eargle horn distortion graph its pretty clear that it increases as frequency goes up (level remaining constant).

    On the other hand both Crowe and Eargle used 2 khz for distortion assessment (in Eargle's case the 2 khz was used for distortion calculation with the formula, which requires that you input a driving frequency and other data, otherwise no calculation. But for measured distortion a number of frequencies were used from 1 khz to 10 khz).

    Surprisingly 10 khz appears to be a more challenging situation than 2 khz. Comparing these might be seen as an unfair comparison. Fine, then give the 10 khz horn above any reasonable handicap (golf language here, lol) and i'm confident it'll still not match the dome's lower distortion.

    Waveguides are a non argument here, the topic isn't waveguide distortion vs dome, but rather horn vs dome. Moreover, what i've seen yet is waveguides for cones and/or domes only: JBL 3 series, Genelec monitors, JBL 4632 Screen Array, etc. Potential horn developments or technology on the drawing board or on a shelf don't help users much. Its more about what guys here actually use, that means many different horns and domes, with a number of older ones.

    Systems distortion isn't relevant either since other components, than horn or dome implicated, may introduce some distortion of their own. When making comparisons everything should be the same as much as possible (same setup), except for one variable, in this case the horn or dome, as Eargle did for the 2360 vs 2352 horn dist.

    Finally, the real and most interesting aspect in Crowe's distortion comparison between horn vs dome (dome in horn H2606) is where it shows this dome has significant lower distortion than horn... Compared to unity, crowe's "only 1.8 times better" (see pic) nevertheless that means 80% less dome distortion! (Btw the H2606 mentioned is pretty similar to my Vifa H25... and Peerless H26... tweeters).

    Richard
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  13. #568
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    Hi Richard,

    I appreciate your citing reference to the Eargle text. However this doesn’t provide a perspective or context needed to determine the diy user case.

    You are forgetting one important thing.

    With the exception of the ATC 150S super mid dome the reality is most dome mid drivers lack useable sensitivity for use with a 15 inch woofer. By this I refer to the sensitivity rated at 1 watt one meter. Many dome mids are only 92 db sensitivity. Using these domes with a passive network makes them completely unsuitable for use with a 15 inch woofer rated at 93-94 db sensitivity at one meter.

    How many people here use an active crossover with a multi way loudspeakers? Only a small minority. So harping on about the virtues of mid domes is largely a theoretical discussion.

    This is a fundamental reason for the continued use of compression drivers with horn loading above 15 inch woofers with passive networks.

    Secondly if you look at published data sheet here the dome mid driver only has a 0.4mm of linear excursion while the power handling is 80 watts. The dispersion of this 3 inch mid dome driver begins to tapper off above 2,000 hertz. This means the diy user must consider a dome tweeter above 2000 but below 3,000 hertz to rescue the dome mid off axis performance. This means the diy user must design a multi way active system to make using a dome mid and dome tweeter with a 15 inch woofer.

    A good horn or wave guide doesn’t have these problems once the response is normalised.

    https://www.falconacoustics.co.uk/do...608-920010.pdf

    I therefore submit on grounds of practicality a horn compression driver combination wins the diy user case.

    Quested, ATC and other studio monitors companies the use dome mid drivers resort to complex active designs to make such systems a viable product. This is normally well outside the scope and capability of a diy loudspeaker hobbyist.

  14. #569
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    Thank you for having posted the Crowe and JBL Tech Note texts relative to this issue, they're providing the context and perspective in order to tackle the problem. Moreover, indicating the JBL HF horn distortion data is actually much worst than Eargle's "best case" type numbers. The 25% and 40% measured are quite large, therefore clearly showing where a major improvememt is deeply needed.

    His theory is that you need a 15"/horn combo. That imperative offered only keeps users swimming in distortion, which btw they would never accept from another component! (e.g. amp), rather than trying helping them out of it or a notable reduction thereof.

    Then he tries to make a case with partial info, using a worst possible dome mid as if it had any relevance, since very few would purchase a mountain shape dome mid response curve. Quite theoretical gymnastics. Who builds speakers using as bad as possible drivers? Probably no one or so, then definitely not a typical case, can't be called serious work.

    For comparison with CD use he promotes, the maximum excursion of a typical JBL 4" compression driver is given at 0.55 mm (pic shown), and for the poor dome he chose to display "only has a 0.4mm of linear excursion" he wrote ( +/- he omitted). Calculating his way leads to a displacement capability difference between the two of only 0.15 (or 1/7th) of a single mm! Far from a biggie, and not very significant.

    In addition, he treats the ATC dome mid like an exception, it isn't. People looking for dome mids, including for the 93 to 97 db sensitivity range, should see for themselves the ones offered (i did). Likewise for high sensitivity dome tweeters. Excluding cheap low-quality units, there remains a number of them for both types, obviously he didn't check.

    Declaring/deciding the solution (need of 15"/horn) without having first established one's needs and goals, duty/use, db spl required, dispersion pattern needed, budget, etc. seems cavalier and sure doesn't help the DIY in making the best choices or decision for his own situation.

    Harping on about horns he missed the most important opportunity he had: providing DIY/users with solutions, even suggestions, leading to a significant reduction of high CD/horn distortion. But he's offered them no alternatives to the problem as if there were only horns. Therefore they'll remain in double digit distortion, for many cases, and passing on the hot potato in DIY/users hands.

    It should be more of a concern than he has shown. In view of his dome denial, plus distortion skepticism, its evident horn users and candidates for such are the ones that need to be rescued, not the junk dome he tried to convince with.

    Reality and/or practicality is horns are mostly useful in PA/SR work, over about 110-115 db level and/or where a specific sound dispersion pattern is important. Such require horns, many others don't or less so. Moreover, there's the case of people who like/prefer horns for whatever reason, good or bad, its their right and money too. But that doesn't mean horns are necessary for the person's use, its rather a personal choice, the result of influence or imposed by a cloning project. Naturally, going the horn way does come with higher distortion to endure...

    In a lot of cases domes are an undeniable, practical and cost effective part of the solution to achieve lesser distortion.

    Between DB's more output and distortion reduction (switching CD): "It is JBL's contention that the reduced distortion is the greater of these two benefits," (From horn document he posted). Thanks.

    Richard

    J. Eargle, Loudspeaker Handbook, 2nd Ed., P. 178
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  15. #570
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    Another Shure VN45MR stylus for my V15 IV cartridge

    Recently i was able to secure a new old stock original. I had lost hope for quite a while in getting one of these at less than sky-high pricing. Make no mistake, this new one was not cheap, still expensive all in. Though much less than what sharks ask for.

    I already own one with very few hours of use, my concern about not finding another made me use it very little to extend the pleasure over time. I figured if i used mine regularly then after a while there would be no treat left, only drought! as they are more difficult to find with time, particularly in new condition i prefer. The number of used ones available rarely tell with some accuracy the actual mileage done with it, too risky purchase.

    Remembering having seen one from another seller's clear pictures where one face on his elliptical diamond appeared to have overuse compared to the other sides. Maybe an anti-skating adjustment problem or lack of proper cart protractor adjustment i suppose.

    Recent ones seen, with or without cart, new or used were $649.US, $999.US, $1240.CAD. These amounts are not only high but on the verge of dementia. I also noted that many Japanese sellers seem to think that North Americans are a bunch of big fish who will take the bait anyway, not my case. Although now with the fragile economy, inflation, lay-offs by the thousands some are starting to come back to reality about life's non-essential devices.

    I resisted bending the knee and giving in, don't like encouraging greedy sellers benefiting from people's misfortune (Shure having discontinued phono stuff some years ago). I haven't participated in any auction yet, since only the last bid matters so you have to be available at the end to win, also you're somewhat shooting yourself in the foot bidding ever higher, auction price can only go up, and i don't really have time for this type of game...

    Initially, seller asking was too high, later he applied a worthy price reduction so i pulled the trigger, didn't wait any longer as this might attract more buyers. I'm even surprised getting it, i guess folks might have snob it. Too bad for them. Got this from Europe. I suppose European people prefer using Ortofon, or some other brand, its their privilege. That's fine it leaves more Shures available for me to purchase...

    I had a little concern about the cantilever not being straight on pics, seller took returns so if bad i could ship it back, but it turned out to be Web picture distortion, glad it is straight. Diamond examination with the small hand-held 50X microscope reveals its like my other one having a dark diamond tip too. No problems detected.

    For a very short time (say 2 sec.) i saw the micro-ridges, but the slightest hand movement is amplified by the microscope so pretty hard to keep that in focus longer, much easier to do with a traditional elliptical diamond or similar. Moreover the cantilever and diamond for the MR stylus are extremely small size and fragile. No mishandling or mistake are allowed here, otherwise a fair amount of money could go down the drain. Rough individuals should consider instead e.g. a Shure SC35C, M75XXX or similar, but you won't enjoy the same performance level.

    For my road test, first did tracking force adjusment, after it went on to the Stevenson protractor to confirm proper alignment, then anti-skating setting, and ready to roll.

    Tested it for almost 3 hours listening to various LPs. e.g. good old Loggins & Messina albums that have a lot of instruments (horns, mandolin, harmonica, violin, etc.). Since i like their music (not all) then why not. The words that kept coming to mind: detail/precision, transparency and soundstage, how nice this is. Transients too.

    Didn't put the stylus damper brush in action, tracking at 1.24 gr. per digital scale. Don't really need using the damper with phono pre rumble filter, and use of a carbon fiber brush to clean the records.

    Needless to say, after use i not only clean the diamond but don't let such stylus hanging around, nor in the tonearm, it goes back in safe storage, just in case something happens. They're simply too hard to get new. All carts being pre-mounted on good shells, its easy to switch with another.

    Not that i don't like aftermarket VN45HE stylus (i have), nor the M95ED cart, but the Micro-Ridge is in a different class, as the best performer Shure made for the V15 IV and V, plus i had some aftermarket stylus quality issues before, something i don't get with the original stuff, up to now.

    I'm familiar with Shures, like the sound, have modified/fixed some, sometimes a stylus is interchangeable with another, and have spare needles for the carts i have. That makes it a no brainer.

    BTW beware of a stylus called VN45MR Shibata offered by some aftermarket seller(s). Maybe trying to make mileage with the name and/or confusion with the MR designation. Possibly because they can't reproduce the Micro-Ridge design. Shibata is something else while the Micro-Ridge is the real thing. I think a Shibata is probably more like Shure's Hyperelliptical in shape/length, and the Micro-Ridge has no real equivalent that i know of.

    Richard
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